Marine structures, inclusive of ships, offshore structures, sea water conduit systems of seaside plants, fishnets, culture rafts and buoys, are favorite habitats of large attached animals and plants, such as barnacles, hard-shell mussels, sea lettuce (green laver), etc., attached diatoma, bacteria and other microorganisms, all of which cause corrosion of these structures, increased seawater resistance of slips, clogging of fishnets which may induce a massive death of the fish caught therein, and increased structure weights which lead to sinking and decreased operation efficiencies.
In order to prevent such damages due to harmful aquatic life, the submerged structures, ships, fishnets and the like have heretofore been coated with antifouling paints which are mostly based on organocopper compounds or organotin compounds. Such paints are usually compounded with, as a part of the coating vehicle, a rosin and the toxicant is usually dissolved out of the coating with the said rosin.
Also, an antifouling paint containing, as a resinous vehicle, a trialkyl tin polymer has been used as an hydrolysis type antifouling paint. In this type of paint, the trialkyl tin polymer is hydrolyzied in a weak alkaline sea water, liberating an organotin compound and and at the same time, the polymer vehicle is connected into a soluble type and is gradually dissolved in sea water together with the toxic organotin compound. In either type of antifouling paints, the dissolved toxicants are very toxic to the sea living, thereby killing or weakening the animals or plants and attaining the antifouling effects desired. These toxicants are also harmful to human beings and hence the heretofore proposed paints have serious problems in respect to safety and hygiene for operators and further result in less pollution of the environment.
The inventors have formerly described in Japanese Patent Application No. 59344/90 (Publication No. 128302/91) a noxious aquatic control agent, containing as a toxicant, an alkyl substituted phenol derivative of the formula: ##STR1## in which R is a straight or branched alkyl having 3 to 21 carbon atoms; A is a hydrogen atom, hydroxy group or a methoxy group; and s is an integer of 1 to 5, providing that at least one A is a hydroxy or a methoxy group. However, an antifouling paint containing the abovementioned phenol derivative is not so useful because of the soluble natures of the toxicant. Furthermore, in Japanese Patent Application No. 224452/62, a coating composition has been proposed containing as a vehicle a reaction product of a silane compound represented by the formula: EQU R.sup.4.sub.t --Si--(OR.sup.5).sub.4-t
in which R.sup.4 is an alkyl group, a haloalkyl group, a cycloalkyl group, an aryl group or an aralkyl group, R.sup.5 is a hydrogen atom, an alkyl group or an cycloalkyl group, and t is 0 or an integer of 1 to 3, and/or its low condensation product, an organic compound having in its molecule at least 2 hydroxyl groups, and a monohydric phenol compound. The coating obtained is said to have a strong and long-lasting antifouling and anti-mold effects due to the strong anti-bacterial and anti-mold activities of the monohydric phenol component attached to the silane and the activities of the main structural portion of the formula: ##STR2## In that patent application, the following are mentioned as examples of the monohydric phenol compound: phenol; alkyl phenols such as o-cresol, m-cresol, p-cresol, 2,3-xylenol, 2,4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol, o-ethyl phenol, m-ethyl phenol, p-ethyl phenol, p-t-amyl phenol, p-t-butyl phenol, p-phenyl phenol, p-cyclohexyl phenol; alkoxy phenols such as m-methoxy phenol; halogen substituted phenols such as o-chlorophenol, p-chlorophenol, 2,4,6-trichlorophenol, pentachlorophenol, 2,4,6-tribromophenol; nitophenols as o-nitro phenol, p-nitro phenol, 2,4-dinitro phenol, 2,4,6-trinitrophenol; amino substituted phenols such as p-dimethylamino phenol; cyano phenols as p-cyanophenol and the like.
However, these phenols are comparatively water soluble and therefore, when hydrolyzed and released in the environment, there are problems in safety. Furthermore, the desired long-lasting antifouling effects cannot be attained because they are, after being hydrolyzed, quickly dissolved out in sea water due to their excellent water solubilities.
Alkoxy, halogen, nitro, amino and cyano substitutede phenols are very highly water soluble, causing harmuful effects in suroundings.
The inventors have also previously proposed in Japanese Patent Application No. 127025/91, an antifouling composition for fishnet use, comprising an alkyl phenol compound of the formula: ##STR3## in which R.sup.6 is a straight or branched alkyl having 4 to 21 carbon atoms; and s is an integer of 1 to 5, a repellent type compound such as silicone oil, and an antifouling agent such as dichlorophenyl dimethyl urea. However, this is likewise still short in antifouling activity and further improvement has long been desired.
In Japanese Patent Application Nos. 286355/89, 316814/89, 55396/88, 21751/88, and 50232/88, it has been proposed to utilize phenol compounds in antifouling paints wherein polymers or copolymers of vinyl monomers are connected to various phenol compounds are connected through ester bonds and also phenol modified resins are employed which are derived from compounds obtained by the addition reaction of various phenols and carboxylic anhydrides. In these polymers, the phenol compounds are connected to the side chains of the polymers through ester bonds and such phenol esters are believed to be quite difficult in the control of their hydrolysis rates in sea water.
It is, therefore, an object of the invention to provide a novel and effective antifouling paint which is free from the abovementioned problems.